248 REPORT OF OFFICE OF EXPERIMENT STATIONS. 



to tho formula 30-30-30-100. This troatmonl did not manifost its 

 cllVcts so quickly as did crudo petrolciiin ('()ini)ar('d with it, i)ut ulti- 

 inatoly the California wash proved equally oifective with the crude 

 potrolouin and did much loss damafjo to the trees. The self-hoiled 

 mixture containiu"; caustic soda appeared to be about as etfective and 

 safe as the ordinary California wash. 



Elaborate chemical studies were made in the Virginia Station « on 

 the compounds produced in the preparation of the California wash 

 when dilferent proportions of the ingredients are used. Judging 

 fioui the behavior of various preparations, it a])peared that when 

 50 pounds of lime and 40 pounds of sulphur were used per 100 gallons 

 of water the addition of salt improved the mixture somewhat. It 

 was found that when different quantities of the various ingredients 

 w^ere used variations in the specific gravity of the mixture resulted. 

 The greater the amount of lime and sulphur used the higher the 

 specific gravity. In tests to determine the length of time during 

 which the mixture should be boiled different samples were boiled for 

 from thirty minutes to two hours. The density of the solution varied 

 somewhat in mixtures which were boiled less than twentj'^ minutes, 

 but after this time the density remained almost constant even when 

 the preparation was boiled for two and one-half hours. Repeated 

 experiments along this line indicated that the mixture remained ap- 

 proximately the same whether boiled thirty minutes or two and one- 

 half hours. As a result of the various tests at the Virginia Station, 

 the formula 30-30-10-100 is recommended. This preparation, when 

 properly boiled and diluted, should test about 1.053 on the hydrometer 

 or about 7° on the Beaume acid spindle. The California wash has 

 been tested extensively as a winter application in Virginia with 

 almost uniformly good results. In cases of bad infestation it is also 

 recommended as a summer treatment to the trunks and main branches 

 of apple trees. The chief value of salt and copper sulphate in 

 sulphur washes is believed to be found in their tendency to cause the 

 wash to adhere better to the trees. One application either in the fall 

 or spring is usually effective. The Oregon wash made according to 

 the formula 80-80-7-360 w^as tested on 50,000 peach and apple trees. 

 The treatment was very effective, although the insecticide was imper- 

 fectly applied, so that some of the scales escaped being touched with 

 the spray. 



As a result of numerous experiments with the California wash in 

 Washington '' various modifications have been made, but the formula 

 recommended at present is 1 pound of sulphur and 1 pound of lime 

 per 4 gallons of water. The salt is considered unnecessary and prob- 

 ably a useless ingredient in this wash. The lime-sulphur wash 



a Virginia Sta. Bui. 141. » Washington Sta. Bui. 56. 



